The present invention relates to the growth of crystalline silicon carbide films at low temperatures using silicon containing cyclobutanes as the source gas in a chemical vapor deposition (CVD) process.
Crystalline silicon carbide is useful in many high temperature, high power and high frequency semiconductor device applications because of properties such as a wide bandgap, high saturated electron drift velocity, high breakdown electric field, high thermal conductivity, and good chemical resistance. However, most all device fabrication processes require the formation of single crystal silicon carbide films. Normally, these films are grown by chemical vapor deposition at temperatures above 1000.degree. C. For instance, Learn et al., Appl. Phys. Let., Vol. 17, No. 1, July 1970, teach the formation of cubic silicon carbide on alpha (6H) and beta (3C) silicon carbide substrates by the reactive evaporation or reactive sputtering of silicon in acetylene at temperatures as low as 1100.degree. C. Similarly, Steckl and Li, IEEE Transactions on Electronic Devices, Vol. 39, No. 1, Jan. 1992, teach the formation of beta (3C) silicon carbide films on carbonized silicon (100) by rapid thermal chemical vapor deposition of silane and propane at 1100.degree.-1300.degree. C.
Other investigators have also demonstrated the deposition of 3C silicon carbide films from organosilicon precursors at elevated temperatures. For instance, Takahashi et al., J. Electrochem. Soc., Vol 139, No. 12, Dec. 1992, teach the formation of 3C silicon carbide on Si(100) and Si(111) substrates (with and without a carbonized layer) by atmospheric pressure chemical vapor deposition using hexamethyldisilane and hydrogen gas mixtures at temperatures of 1100.degree. C.
Golecki et al., Appl. Phys. Lett, 60 (14), April 1992, teach the formation of cubic silicon carbide on silicon (100) substrates by low pressure chemical vapor deposition using methylsilane at substrate temperatures as low as 750.degree. C. The process described therein, however, is solely limited to the use of methylsilane as the precursor gas.
The use of silicon containing cyclobutanes to form amorphous or polycrystalline silicon carbide films is also known in the art. For instance, Tarhay et al. in U.S. Pat. No. 5,011,706, teach the formation of amorphous silicon carbide coatings by low temperature plasma enhanced chemical vapor deposition using a silicon containing cyclobutane. Similarly, Larkin et al., Mat. Res. Soc. Symp. Proc. 204, 141 (1991) teach the formation of polycrystalline silicon carbide films on silicon (100) substrates by low temperature chemical vapor deposition using substituted 1,3-disilacylobutanes. Likewise, Johnson et al., Mat. Res. Soc. Symp. Proc (November 1992) teach the formation of amorphous silicon carbide films by the thermal decomposition of silacyclobutane at temperatures in the range of 650.degree.-1050.degree. C. As is evident from the above descriptions, however, neither of these references teach the formation of crystalline silicon carbide.
The present inventors have now discovered that crystalline silicon carbide films can be deposited at relatively low temperatures using silicon containing cyclobutanes in a chemical vapor deposition process.